A motor is an important component of an aircraft (e.g., an airplane). A motor, however, may fail. For example, a motor may fail due to an open circuit or stall condition, which may result in an inability to move the motor.
One type of motor used in aircraft is a so called stepper motor. A stepper motor is controlled by an external control circuit, such as a microcontroller. To make the motor shaft turn, first, one electromagnet is given power, which makes the rotor magnetically attracted to the electromagnet's poles. When the next electromagnet is turned on and the first is turned off, the rotor rotates slightly to align with the poles of the next one, and from there the process is repeated. Each of those slight rotations is called a “step” and is made upon the issuance of a step command by the control circuit.
Detection of a failed stepper motor is typically based on a position tracking function. Using position tracking results in a delay from a time of the failure until a time that the failure is detected. Moreover, the fault may go undetected until a reposition command (e.g. the next “step command”) is provided.